Previously, researchers had noticed that clusters contain many more elliptical galaxies than spirals, hinting that newcomer spirals were somehow being transformed. Harald Ebeling at the University of Hawaii in Honolulu and his colleagues think jellyfish galaxies capture the process in action (Astrophysical Journal Letters, doi.org/q7q).

Hot gas in the space between clustered galaxies smacks into cold gas within a new arrival, blasting gas outwards in streams. The stripped body of the galaxy settles into a blobby shape, while cold gas in the tendrils compresses enough to ignite new stars.

This article appeared in print under the headline “Jellyfish galaxies caught in clusters”